During grinding and other machining opertions gauges are commonly utilized to measure the size of a workpiece. One of these known gauges is disclosed in U.S. Pat. No. 3,681,582 and includes a pair of gauging members or calipers which are moved relative to each other by screw and nut drive arrangements. A magnetic scale and reading head are utilized to measure the position of the gauge members relative to each other. Other known gauging devices are disclosed in U.S. Pat. Nos. 2,826,818; 3,109,265; 3,568,372; 3,688,411; 3,745,660; 3,755,909; 3,781,997; and 3,851,396.
Although these known gauge assemblies are more or less satisfactory in their construction and mode of operation, it is believed that they do not provide optimum gauging characteristics. Accordingly, there is a need for an accurate automatically adjustable gauge assembly that can measure a range of workpiece diameters, such as on multiple diameter shafts. This in-process adjustable gauge should have an accurate reader to provide the necessary feedback in order to allow a numerically controlled machine to achieve the desired grinding tolerances. In addition, the gauge should have a repeatable and accurately determined gauging pressure in order to provide repeatable accuracy in the measuring of parts having a tolerance range of 0.0001 inches on the diameter. In order to provide for accurate measurement of parts with these tolerances, a consistent gauging force must be applied to the part by the gauge members or calipers.